How do I bake a texture using Cycles bake
With out more detail about the situation, it's hard to say how you might go about this if there are any special considerations.

Here are the basics:


UV unwrap your object.
Create a new image in the UV/image editor (Alt + N or Image > New).
Add a texture node to the objects material(s) and select the new image. If there are more than 1 material repeat this for each one of them (easier to copy that Image Texture node and paste it into all materials):


With the texture node selected, press bake in Properties > Render settings > Bake:




The color and shading on that object will be rendered to the image specified in the selected texture node.

If you switch to textured shading once this process is complete (for each object), the viewport will look something like this:



See the wiki for more detail about the various options.

If you want to bake multiple objects to the same image:


UV Unwrap your objects in such a way so that the UV maps don't overlap. An easy way to do this is by pressing Space> Smart UV unwrap or Space> Lightmap pack with all the objects selected.
Bake each object with Clear disabled so that the existing pixels in the target image aren't erased before the baked shading is overlayed.